Table 1.
Network Statistics by Payer Source: Medicare Vs. Private Insurance
| Statistic (1) | Medicare (2) | Private (3) | Medicare subsample average (4) | p value for difference between (3) and (4) |
|---|---|---|---|---|
| Number of patients | ||||
| Total | 41,167 | 13,272 | 13,026 | < 0.001 |
| Unshared | 14,328 | 4886 | 4960 | 0.052 |
| Providers | ||||
| Total number | 1735 | 1321 | 1097 | < 0.001 |
| % surgeons | 56.369 | 55.715 | 54.333 | < 0.001 |
| % medical oncologists | 29.452 | 30.961 | 31.057 | < 0.001 |
| % radiation oncologists | 14.179 | 13.323 | 14.610 | < 0.001 |
| Provider patient sharing | ||||
| # of patients shared across all three specialties* | 4346 | 1202 | 1196 | 0.427 |
| # of patients shared between at least two specialties | 19,615 | 6188 | 5829 | < 0.001 |
| Average degree† | 43.979 | 26.044 | 27.242 | < 0.001 |
| Average edge-weighted degree‡ | 193.911 | 80.324 | 83.259 | < 0.001 |
| Average fraction shared§ | 0.134 | 0.226 | 0.127 | < 0.001 |
| Provider-to-provider connections | ||||
| Relative centrality‖ | ||||
| Surgeon | 0.096 | 0.142 | 0.118 | < 0.001 |
| Medical oncologist | 3.673 | 4.683 | 3.964 | < 0.001 |
| Radiation oncologist | 2.404 | 1.340 | 1.821 | < 0.001 |
| Average clustering coefficient¶ | 0.513 | 0.535 | 0.523 | < 0.001 |
| Global clustering coefficient# | 0.278 | 0.268 | 0.297 | < 0.001 |
| Size of largest connected component** | 1659 | 1286 | 1082 | < 0.001 |
*Specialties are surgeon, medical oncologist, and radiation oncologist
†Degree is the number of other providers with whom a provider shares patients
‡Edge-weighted degree (node strength) is the number of other providers with whom a provider shares patients weighted by the number of patients shared with each provider
§Fraction shared is the fraction of a provider’s patients who are shared with any other provider
‖Provider-specific relative centrality is defined here by the average betweenness (weighted by edges) of all providers of a given specialty divided by the average betweenness of all providers not in that specialty
¶Clustering coefficient is the proportion of providers with whom a provider shares patients who also share patients with one another
#Fraction of connected triplets that form a closed triangle
**Size of the largest subgraph that is contiguously connected